Distribution of groups with at least 12 member galaxies in our superclusters in the Cartesian coordinates as in Fig. 3, in units of h^-1Mpc. Filled circles denote the groups with at least 50 member galaxies, empty circles denote the groups with 30–49 member galaxies and crosses denote the groups with 12–29 member galaxies. The numbers show the ID’s (Table 1, Col. 1) of very rich superclusters from Sect. 4.3.